The present Application relates at least generally to the field of mobile storage and supply of electrical energy and, more importantly, to an advanced mobile energy storage device and associated methods.
Applicants recognize there is a need for improvement in the supply of electrical energy in places and situations where connection to the electrical grid is inconvenient or impractical. Examples of these situations include construction sites, outdoor recreation such as camping, and emergencies such as the aftermath of storms. The prior-art has attempted to provide at least somewhat effective solutions using fossil fuel powered generators, with their incumbent detractions such as noise, exhaust, size, maintenance requirements, and the like. Portable generators for these situations usually supply a replacement grid connection: for example, 120-volt ac outlets. In addition, there has been a recent explosion in the market for mobile devices such as music players, LED lights, and wireless communication devices such as cellphones and tablets, among others. These mobile devices are typically powered by batteries, which need to be recharged, expanding the need and applications for the supply of electrical energy in off-grid situations.
Applicants further recognize that improvements in the size and cost of dc-to-ac converters, or inverters, have made practical the use of batteries to replace generators in these situations. A battery/inverter solution has many advantages over the detractions associated with fossil fuel powered generators: it is quiet, clean, more reliable, and can be much smaller, lighter, and more portable. Furthermore, recent improvements in battery chemistries have produced much higher energy storage densities, further enhancing the mobility of a battery/inverter supply. Batteries, even high energy density technologies, store only a finite amount of energy and therefore are in need of periodic recharge. The usual way this is done is with a charging circuit that is connected, at least temporarily, to the electrical grid, commonly through a 120-volt ac outlet. The charging circuitry can be incorporated into the same structure with the battery and inverter and this has led to the mobile energy storage device. The MESD (Mobile Energy Storage Device) has become a popular solution for applications ranging from single-digit watt, pocket-sized devices to multi-kilowatt generator replacements.
FIG. 1 is a block diagram that illustrates a prior-art mobile energy storage device, or MESD, generally indicated by the reference number 100. Electrical energy is stored in a rechargeable battery 101 of any suitable chemistry. The energy is made available for use by external devices on an ac power output 102, a USB (i.e., 5 volts) output 103, and a dc output (i.e., 12 volts) output 104. The battery can be recharged by connecting an ac power input 105 of the MESD to the electrical grid, (plugging it in to an electrical outlet). Some prior-art mobile energy storage device embodiments have an additional dc power input 106, frequently a 12-volt input suitable for connecting to the electrical system of an automobile, allowing recharging in locations without an electrical grid connection. Frequently, there are user controls 107 to provide functions such as the enabling/disabling of power outputs and the starting/stopping of recharging through the power inputs. There is also frequently a display 108 indicating to the user the status of the power inputs and outputs. The display can also indicate the state of charge (SOC) of the battery, i.e. the amount of energy stored within the battery. This is often indicated as a fraction of the capacity of the battery. Applicants observe that displaying the SOC when a mobile energy storage device is powering external devices can be of little value, as will be discussed at appropriate points below.
Applicants recognize that the prior-art has not addressed problems and concerns that have been swept aside by the advancements that have been brought to light hereinafter. Accordingly, the foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art may become apparent to those of ordinary skill in the art upon a reading of the specification and a study of the drawings.